Cylindrical body of fiber drum and method of fabricating the cylindrical body

ABSTRACT

A cylindrical body of a fiber drum comprises a roll of a paper material having two opening ends, a curled portion formed by curling the edge of at least one of said two opening ends and a protective material for covering outer surface of the curled portion. A method of fabricating a cylindrical body of a fiber drum comprises the steps of winding a length of paper sheet in layers, between which an adhesive is applied, to form a roll of the paper sheet having two opening ends, providing a protective material on an opening edge at either of the two opening ends of the roll, and curling inwardly or outwardly the opening edge at said either of the two opening ends of the roll together with the protective material before the adhesive is cured between the layers to form a curled portion covered at an outer surface with the protective material.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a cylindrical body of a papermaterial constituting a fiber drum and a method of fabricating thecylindrical body.

[0003] 2. Prior Art

[0004] A conventional cylindrical body of a fiber drum is made of a rollof a paper material and its opening edges at both upper and lower endsof the roll are inwardly curled together with metal rings forreinforcement thus forming inwardly curled annular portions.

[0005] When the fiber drum is used for storage of powder or granules ofmedical product or fine chemical, it may be provided with an inner bagor container made of a synthetic resin material for being air-tightlyfilled with the powder or granules. Yet, if the inner bag or containeris fouled with dusts of the paper material of the cylindrical body, itmay appear as being suffered from leakage or contamination with thepaper dusts and its quality management will hardly be qualified.Accordingly, it is a major issue to inhibit the generation of paperdusts.

SUMMARY OF THE INVENTION

[0006] The present invention is developed in view of the above aspectsand its object is to provide a cylindrical body of a fiber drum whichcan prevent the generation of paper dusts while the opening edges of aroll thereof are being shaped, improve the physical strength of theopening edges, and facilitate its recycling and a method of fabricatingthe cylindrical body.

[0007] For achievement of the object, a cylindrical body of a fiber drumaccording to the present invention is featured in which at least oneopening edge or the other opening edge of a roll made of a cylindricalpaper material has a curled portion thereof inwardly or outwardly curledand protected at its outer surface with a protective material. This willincrease the physical strength of the one or other opening edge. Also,if the curled end of the curled portion is injured or cracked, its outersurface is protected with the protective material thus inhibiting paperdusts generated at the injury or cracks from dispersing to the outside.

[0008] The protective material may preferably be a length of paper tape.This will require no particular separation of the protective materialfrom the roll during the disposal process.

[0009] A method of fabricating the cylindrical body of a fiber drumaccording to the present invention is provided comprising the steps ofwinding a length of paper sheet in layers, between which an adhesive isapplied, to form a roll; providing a protective material on the openingedge at either one or other opening end of the roll; and curlinginwardly or outwardly the opening edge at either one or other openingend of the roll together with the protective material before theadhesive between the paper layers are completely cured to form a curledportion covered at the outer surface with the protective material. Asthe curled portion is formed within a short period of time, a number ofthe cylindrical bodies can be fabricated at higher efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a perspective view of a cylindrical body showing oneembodiment of the present invention;

[0011]FIG. 2 is a cross sectional view of one side of the cylindricalbody according to the embodiment of the present invention;

[0012]FIG. 3 is a partially enlarged cross sectional view of thecylindrical body according to the embodiment of the present invention;

[0013]FIG. 4 is an explanatory view showing a process of forming a greenroll of the cylindrical body;

[0014]FIG. 5 is a cross sectional view of one side of the cylindricalbody where its roll is protected with a protective tape material;

[0015]FIG. 6 is a front view of a forming machine;

[0016]FIG. 7 is a cross sectional front view showing the roll placed inthe forming machine;

[0017]FIG. 8 is an enlarged cross sectional view of a primary part ofthe roll with a curled portion provided at one opening edge thereof;

[0018]FIG. 9 is a cross sectional front view showing an action of thecurled portion being outwardly expanded by a forming die;

[0019]FIG. 10 is a cross sectional front view showing the curled portionfractured with a chuck;

[0020]FIG. 11 is a partially enlarged cross sectional view of acylindrical body showing another embodiment of the present invention;

[0021]FIG. 12 is a perspective view of the cylindrical body of theanother embodiment of the present invention;

[0022]FIG. 13 is a cross section view of one side of the cylindricalbody of the another embodiment where its body is protected with aprotective tape;

[0023]FIG. 14 is partially enlarged cross sectional view of thecylindrical body of the another embodiment of the present invention; and

[0024]FIG. 15 is partially enlarged cross sectional view of thecylindrical body of the another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Some embodiments of the present invention will be described inmore detail.

[0026]FIG. 1 is an external view of a cylindrical body of a fiber drumshowing one embodiment of the present invention and FIG. 2 is a frontview showing the cross section of one side of the cylindrical body. FIG.3 is a partially enlarged cross sectional view of the cylindrical body.

[0027] As shown, the cylindrical body 1 of the fiber drum comprises aroll 2 made of a paper material and a protective tape 3 of a papermaterial provided as a protective member. The roll 2 may be fabricatedby rolling a thick paper board into a cylindrical form or a plurality ofpaper sheets into a multi-layer form which will be explained later inmore detail. The protective tape 3 may be a length of craft tape havingan adhesive coating provided on the back side thereof.

[0028] As shown in FIGS. 1 to 3, one edge at one opening 4 of the roll 2is inwardly curled to form a curled portion 5 of an annular form whichextends circumferentially and has an oval shape in the cross section.The protective tape 3 is bonded to the circumference of the curledportion 5. The curled portion 5 is pressed down together with theprotective tape 3 so that its inner cavity is eliminated.

[0029] Similarly, the edge at the other opening end 6 of the roll 2 iscurled to have a curled portion 7 which is identical in the shape to thecurled portion 5 provided at the edge of the opening end 4. The curledportion 7 like the curled portion 5 is protected with another protectivetape 3 and pressed down by the same manner.

[0030] As both the roll 2 and the protective tape 3 of the cylindricalbody 1 are made of paper materials, they need not separation during thedisposal process of the cylindrical body 1 but can easily be recycledfor reuse.

[0031] The two curled portions 5 and 7 are protected with thecorresponding protective tapes 3 and even if they are wrinkled andinjured when being curled and thus produce paper dusts, the protectivetapes 3 can inhibit the paper dusts from being scattered out to theoutside.

[0032] Also, the curled portions 5 and 7 are pressed down so that theirinner cavities are eliminated and their physical strength will beincreased.

[0033] The protective tapes 3 of the embodiment is made of, but notlimited to, the craft tape having the adhesive layer provided on theback side thereof. For example, the protective tapes 3 may be made of asynthetic resin material such as poly-propylene tape or cellophane tape.Those materials of tape can equally inhibit paper dusts generated at thereinforcement of the opening end or any crack of the edge from beingscattered out.

[0034] A method of fabricating the cylindrical body 1 will now bedescribed.

[0035] The method starts with a step of forming a green cylindrical bodyla as shown in FIG. 4. More specifically, a length of paper sheet Scoated at its upper side with an adhesive Q before curing is wound inseven to eight layers on the mandrel of a drum forming machine (notshown) to form a roll 2 of the green cylindrical body la. The adhesive Qmay be any commercially available hydrophilic adhesive composed mainlyof e.g. poly-vinyl acetate emulsion or poly-vinyl alcohol.

[0036] Then, a protective tape (a protective member) 3 of a papermaterial which has an adhesive coating provided on the back side thereofand a synthetic resin coating provided on the front side thereof iscircumferentially applied to the outer surface of each of edges 81 and82 at both opening ends of the green cylindrical body la, hencecompleting the roll 2.

[0037] The width of the protective tapes 3 are so sized as to covercompletely the curled ends 5 a and 7 a of their respective curledportions 5 and 7 (See FIGS. 2 and 3).

[0038] The protective tapes 3 maybe applied as slightly spaced from theopening edges 81 and 82 so long as covering completely the curled ends 5a and 7 a of the curled portions 5 and 7.

[0039] The roll 2 is then transferred to a curled portion forming stepwhich may be carried out by a forming machine M shown in FIG. 6. Theforming machine M performs a sequence of three steps, (1) the first stepof inwardly curling both edges 81 and 82 of the roll 2, (2) the secondstep of increasing the cross section of each inwardly curled portionradially and outwardly, and (3) the third step of pressing down theinwardly curled portions.

[0040] The forming machine M has a forming die 9 of substantially acircular shape in the plan view placed on a platform 10 supported by thefloor bed and fixedly held at an intermediate of its outer side with anannular chuck support 11. A first chuck 12 a and a second chuck 12 bwhich travel forward and backward on the horizontal are provided on theupper side of the chuck support 11.

[0041] The first chuck 12 a located upper has a guide region 13 providedon the inner wall thereof for inwardly curling the edge of the roll withits guiding surface 131.

[0042] The inner wall of the second chuck 12 b located lower is a tapersurface 14 which is tilted to increase the opening towards the lower endand opposite to a taper surface 14 of the outer side of the forming die9 tilted at the same angle. A vertically movable pressing member 16 isprovided precisely above the forming die 9 for pressing down the roll 2against the forming die 9.

[0043] In action, the roll 2 of the layers of the paper sheet S beforethe adhesive Q is cured is loaded and placed upright on the guide region13 of the first chuck 12 a as shown in FIG. 7. While FIG. 7 illustratesthe edge at the other opening 6 for simplicity of the description, theedge at the one opening 4 of the roll 2 can also be shaped after turnedup side down.

[0044] When the pressing member 16 is lifted down, the opening edge 81moves along and on the guiding surface 131 as shown in FIG. 8. As theprotective tape 3 slides directly along the guiding surface 131 of theguide region 13 and the taper surface 14 of the first chuck 12 aextending continuously from the guide region 13, the edge 81 is inwardlycurled to form the curled portions 5 and 7.

[0045] When pressed down, the inner layers of the paper sheet S of theroll 2 lag behind the outer layers due to a difference in the curvatureradius at the curled portion 5 or 7. The layers of the paper sheet Swhen curled are not separated but remain bonded to each other by theaction of the adhesive Q. Also, the adhesive serves as a lubricant toassist the lagging. Simultaneously, as the layers of the paper sheet Sare curled, portions of the adhesive Q between the layers of the edge 81of the roll 2 are squeezed out hence running over the inner side of theroll 2. As a result, the portions of the adhesive Q may contribute tothe higher adhesivity and when cured, the improved rigidity of thecurled portions 5 and 7.

[0046] By the above manner, the curled portions 5 and 7 of the roll 2are formed at the one opening 4 and the other opening 6 respectively. Asknown, the curled portions 5 and 7 are instantly formed in a sequence.Then, as the adhesive Q is cured between the layers of the paper sheetthus to turn to an adhesive Qa, the curled portions 5 and 7 areincreased in the rigidity.

[0047] This is followed by retracting the first chuck 12 a from thecurled portion 7 and lifting down the pressing member 16 further asshown in FIG. 9. As moved along the taper surface 15 of the outer sideof the forming die 9, the curled portion 7 is turned outwardly. If thetilting angle is too large, the curled portion 7 may have flawsextending radially. It is hence essential to determine an appropriateangle of the tilting for eliminating the generation of flaws.

[0048] As shown in FIG. 10, the tilted curled portion 7 is held directlywith the taper surface 15 of the forming die 9 and then the second chuck12 b is advanced in the direction X denoted by the arrow in FIG. 10 topress down the curled portion 7. Any hollow space in the curled portion7 may decline the physical strength at the opening of the roll 2. Thepressing down of the curled portion 7 may require a pressing force toprevent formation of any hollow space.

[0049] As described above, the curled portions 5 and 7 are covered withthe protective tapes 3. Accordingly, the curled portions 5 and 7 are notonly reinforced in rigidity but also can be prevented from its paperdusts at any crack being scattered out. Also, as the protective tapes 3are applied at a fair tension, they can protect the curled portions 5and 7 from being cracked and when any crack is developed, may minimizeits effect. Moreover, as the protective tapes 3 are slippery on theupper side, they allow the edges 81 and 82 to slide directly on theguiding surface 131 and the taper surface 14 of the forming die 9 untilthe curled portions 5 and 7 are completed. Accordingly, the curledportions 5 and 7 are less susceptible to the cracking or injury.

[0050] It is a good idea that when the adhesive Q is about cured beforethe curled portions 5 and 7 are completely shaped, the body is heated upfor softening the adhesive Q between the layers of its paper sheet. Ifthe adhesive Q is of a hot melting type, it has to be heated to higherthan its melting point.

[0051] While the curled portions 5 and 7 of the embodiment arefabricated, but not limited to, by inwardly curling the two edges 81 and82 at both opening ends 4 and 6 of the roll 2, they may be shaped by anyother manner. For example, as shown in FIG. 11, each edge 81 (82) of theroll 2 may inwardly be folded down to form a curled portion 51 (71). Asthe folded ends 5 a and 7 a of their respective curled portions areequally protected with protective tapes, their physical strength at theopening will be enhanced.

[0052] The protective tapes 3 may be applied circumferentially to theinner sides of the opening edges 81 and 82 at both ends of a greencylindrical body la to form a roll 2 as shown in FIG. 13. Then, eachopening edge 81 (82) at one opening 4 or other opening 6 of the roll 2is outwardly curled to form a curled portion 52 (72), as shown in FIGS.12 to 14. Alternatively, each opening edge 81 (82) of the roll 2 mayoutwardly be folded down to have a curled portion 53 (73) as shown inFIG. 15. In any case, the generation of paper dusts can be inhibitedwhile the physical strength of the edge at each opening is improved.

[0053] The above embodiments of the present invention are not limited tothe opening edges 81 and 82 provided with their respective curled orfolded portions 5 (51, 52, or 53) and 7 (71, 72, or 73) but may permitone of the two opening edges 81 and 82 to be accompanied with the curledor folded portion.

What is claimed is:
 1. A cylindrical body of a fiber drum comprising: aroll of a paper material having two opening ends; a curled portionformed by curling the edge of at least one of said two opening ends; anda protective material for covering outer surface of the curled portion.2. A cylindrical body of a fiber drum according to claim 1 , wherein theprotective material is a length of paper tape.
 3. A method offabricating a cylindrical body of a fiber drum comprising the steps ofwinding a length of paper sheet in layers, between which an adhesive isapplied, to form a roll of the paper sheet having two opening ends,providing a protective material on an opening edge at either of the twoopening ends of the roll, and curling inwardly or outwardly the openingedge at said either of the two opening ends of the roll together withthe protective material before the adhesive is cured between the layersto form a curled portion covered at an outer surface with the protectivematerial.